Temperature response of litter and soil organic matter decomposition is determined by chemical composition of organic material
2013 (English)In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 19, no 12, 3858-3871 p.Article in journal (Refereed) Published
The global soil carbon pool is approximately three times larger than the contemporary atmospheric pool, therefore even minor changes to its integrity may have major implications for atmospheric CO2 concentrations. While theory predicts that the chemical composition of organic matter should constitute a master control on the temperature response of its decomposition, this relationship has not yet been fully demonstrated. We used laboratory incubations of forest soil organic matter (SOM) and fresh litter material together with NMR spectroscopy to make this connection between organic chemical composition and temperature sensitivity of decomposition. Temperature response of decomposition in both fresh litter and SOM was directly related to the chemical composition of the constituent organic matter, explaining 90% and 70% of the variance in Q10 in litter and SOM respectively. The Q10 of litter decreased with increasing proportions of aromatic and O-aromatic compounds, and increased with increased contents of alkyl- and O-alkyl carbons. In contrast, in SOM, decomposition was affected only by carbonyl compounds. To reveal why a certain group of organic chemical compounds affected the temperature sensitivity of organic matter decomposition in litter and SOM, a more detailed characterisation of the (13) C aromatic region using Heteronuclear Single Quantum Coherence (HSQC) was conducted. The results revealed considerable differences in the aromatic region between litter and SOM. This suggests that the correlation between chemical composition of organic matter and the temperature response of decomposition differed between litter and SOM. The temperature response of soil decomposition processes can thus be described by the chemical composition of its constituent organic matter, this paves the way for improved ecosystem modelling of biosphere feedbacks under a changing climate. This article is protected by copyright. All rights reserved.
Place, publisher, year, edition, pages
Wiley-Blackwell, 2013. Vol. 19, no 12, 3858-3871 p.
CO2, CP-MAS NMR, decomposition, forest, litter, organic chemical composition, Q10, soil organic matter, temperature sensitivity
Biochemistry and Molecular Biology
IdentifiersURN: urn:nbn:se:umu:diva-82400DOI: 10.1111/gcb.12342PubMedID: 23907960OAI: oai:DiVA.org:umu-82400DiVA: diva2:661077
FunderSwedish Research Council, 2009-3060